refactor: centralize email internationalization handling (#22752)

Co-authored-by: Claude <noreply@anthropic.com>

api/tasks/mail_enterprise_task.py

@@ -1,15 +1,17 @@
 import logging
 import time
+from collections.abc import Mapping
 
 import click
 from celery import shared_task  # type: ignore
 from flask import render_template_string
 
 from extensions.ext_mail import mail
+from libs.email_i18n import get_email_i18n_service
 
 
 @shared_task(queue="mail")
-def send_enterprise_email_task(to, subject, body, substitutions):
+def send_enterprise_email_task(to: list[str], subject: str, body: str, substitutions: Mapping[str, str]):
     if not mail.is_inited():
         return
 
@@ -19,11 +21,8 @@ def send_enterprise_email_task(to, subject, body, substitutions):
     try:
         html_content = render_template_string(body, **substitutions)
 
-        if isinstance(to, list):
-            for t in to:
-                mail.send(to=t, subject=subject, html=html_content)
-        else:
-            mail.send(to=to, subject=subject, html=html_content)
+        email_service = get_email_i18n_service()
+        email_service.send_raw_email(to=to, subject=subject, html_content=html_content)
 
         end_at = time.perf_counter()
         logging.info(